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InstruTECH ITC-18:
16-bit data acquisition interface
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All synchronous analog and digital channels are
optically isolated
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Eight simultaneously sampling differential analog input
channels
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Eight 18-bit 200 kHz A/D converters
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200 kHz to 12 Hz sampling in 1.25 µS steps (200 kHz max
aggregate)
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Programmable input gain: 1x, 2x, 5x, 10x
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Analog input range: + 10.24 Volts
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Four pseudo differential analog output channels
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Four 18-bit instrumentation grade D/A converters
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Analog output range: + 10.24 Volts
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Sixteen synchronous digital input channels
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Thirty-two synchronous digital output channels, fourteen
with current sink
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Sixteen asynchronous digital output channels
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Large 1024 kilosample FIFO now included at no additional
cost
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PCI, and USB 2.0 host interfaces available
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Easy installation, no IRQ or DMA channel settings
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Compatible with Windows9x, ME, NT, 2000, XP, MacOS classic,
MacOS X (PPC and intel), LabView for Windows, MatLab and Linux
ITC-18, the second generation low-noise 16-bit data
acquisition interface designed by InstruTECH. The ITC-18 offers
unsurpassed capability while retaining all of the exceptional features of
its predecessor, the ITC-16. The ITC-18 provides a major improvement
in the quality of acquired data, making measurements that would otherwise
not be possible.
Hardware Configuration
The ITC-18
is an external rack-mountable data acquisition unit that is attached to the
computer using a dedicated host interface. This configuration offers
major advantages over traditional data acquisition designs. One
advantage is noise performance. Most data acquisition devices are
printed circuit boards installed directly into the computer. The
interior of a computer is an electrically noisy environment that will
dramatically affect the noise performance of high speed D/A and A/D
converters. Mounting all of the analog electronic components in an
external box provides the most effective means of shielding the analog
signal from this noise.
Another
advantage is the capability to use the analog front end (ITC-18 rack unit)
with a variety of host interfaces. Moving the ITC-18 from one
computer platform to another is a simple matter of using the appropriate
host interface, and installing compatible software. Utilizing the
same hardware when changing computer platforms provides a cost effective
upgrade path to newer computer technologies without sacrificing your
initial investment. Since the ITC-18’s initial inception we have designed
host adapters to interface to various computer bus architectures (i.e. ISA,
NUBUS, PCI, and USB 2.0).
Optical Isolation
The
analog electronics of the ITC-18 are optically isolated from the digital
circuitry of the computer. This provides complete electrical
isolation between the computer and the measuring equipment. Computers
contain digital electronics that switch at high speed, producing large
electrical transients. The computer ground functions as the return
path for these transients, resulting in substantial high-frequency ground
noise. The ITC-18 has a completely separate analog ground that is
isolated from the computer ground. With the ITC-18 computer ground
noise is not coupled into the measurement.
Optical
Isolation is essential if low-noise analog outputs are desired.
The
optical isolation of the ITC-18 brings with it another benefit that
simplifies complex measurement systems. Since the analog inputs and outputs
of the ITC-18 float with respect to power ground, the ITC-18 and the
computer are not a source of ground loop problems.
Analog I/O
A unique
design characteristic of the ITC-18 is the synchronization of all analog
and digital signals. All inputs and outputs are updated
simultaneously. Most data acquisition devices on the market do not do
this. They sample multiple channels by using a multiplexer.
This means that there is a time delay between the samples from each
channel. This makes timing correlation measurements difficult.
The
ITC-18 provides eight analog input channels. Each input channel uses
an 18-bit A/D converter preceded by a programmable gain stage. Each
A/D input can be programmed with a full scale range of +1, +2,
+5, or +10 Volts. This gain stage reduces the need for
external signal amplifiers before the ITC-18. Using separate A/D
converters for each analog input channel also has other advantages.
One benefit gained by using separate A/D converters is reduced crosstalk
between channels. The same multiplexer mentioned in the previous
paragraph, is the source of another disadvantage. It is a single
point where all of the analog input signals connect. This point,
where the analog signals come together, can introduce cross coupling
between the signals. The amount of crosstalk will vary based on
frequency and amplitude. High-frequency signals show the greatest
coupling into other channels while large amplitude signals will also couple
into smaller signals. The ITC-18 has no measurable cross talk between
channels.
The
ITC-18 provides four 18-bit instrumentation grade D/A converters featuring
high accuracy with less than 1 bit (~300 µV) of
noise. This extremely low noise allows for the observation of least
significant bit transitions. The D/A circuitry used in the ITC-18 is
temperature stabilized and “De-glitched” for ideal performance. A
typical D/A circuit will have a large glitch energy around zero and major
bit transitions, the ITC-18's D/A converters are free from this artifact.
The
ITC-18 uses a “sequence RAM” to control the sampling order of both the
analog and digital channels. This provides the ability to update
individual channels at different rates. This arrangement optimizes
the acquisition of signals with dissimilar bandwidth.
This
architecture makes the ITC-18 particularly important when making
measurements using high-frequency signal sources, multiple signal sources
with large differences in amplitude between them or when analyzing multiple
signals for timing correlation.
Digital I/O
The ITC-18 provides sixteen digital inputs, thirty-two
digital outputs, seven sequence RAM trigger outputs and fourteen
asynchronous non-isolated digital outputs. The digital input channels
feature level sensitive or latched modes. For maximum versatility the
inputs can be inverted, allowing rising or falling edge triggering.
Thirty-two digital output channels in two banks of sixteen, with fourteen
channels paralleled with current sink circuitry for driving perfusion
valves or other devices directly. Seven programmable trigger outputs
for triggering from any location in the scanning sequence RAM and fourteen
asynchronous auxiliary digital outputs that can be updated at any time
regardless of the ITC-18's acquisition state. ITC-18’s that use a
USB-18 host interface have an additional sixteen asynchronous non-isolated
digital inputs and outputs.
FIFO Memory
The
ITC-18 is supplied with a large 1024 kilosample FIFO memory for input and
output data. The ITC-18 allows data acquisition to be performed
independent of the activity of the host computer. A large FIFO memory
allows uninterrupted continuous hi-speed acquisition with today’s
multitasking operating systems.
Specialized Applications
The
ITC-18 uses programmable gate arrays that allow the internal hardware to be
altered for specialized applications. One available application is the Artificial Synapse Dynamic Clamp.
The clamped cell is connected to an A/D input via a Voltage Clamp
amplifier. The stimulus is computed, based on voltage measured from
the cell, lookup tables for excitation, inhibition and conductance values
and other parameters. This stimulus is applied to the cell via the
current input of the Voltage Clamp amplifier.
Available Host Interfaces
PCI-18
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The PCI-18 host interface card is
a short form factor, 32-bit, 33 MHz 5Volt PCI bus plug in card. The
PCI-18 is compatible with Apple, PC, and other computer systems that
feature a 5Volt PCI Bus. Please note that the PCI-18 can only be
physically connected to a 5Volt or Universal PCI bus connector.
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PCI-18V3
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The PCI-18V3 host interface card is a short form factor,
32-bit, 33 MHz 3.3Volt PCI bus plug in card. The PCI-18V3 is
compatible with Apple G5, PC, and other computer systems that feature a
3.3Volt PCI Bus. Please note that the PCI-18V3 can only be
physically connected to a 3.3Volt or Universal PCI bus connector.
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USB-18
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The
USB-18 host interface is a USB v2.0 high-speed (480Mbps) interface for
Apple, PC, and other computer systems that feature USB v2.0 high-speed
ports.
An
extra feature of the USB-18 is the addition of sixteen asynchronous
digital input and output lines.
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Technical Specifications
Analog Input:
Number of channels 8,
differential, optically isolated
Type of ADC successive approximation
Input connector BNC
Resolution 18-bit converter,
16-bit data
(1 in 65536)
Acquisition rate 200 kHz aggregate
Input range -10.24 to +10.239 Volts
Aperture delay 10 ns
Aperture jitter 50 ps RMS
Conversion speed software selectable,
5 µs min
Differential nonlinearity +0.002% of FSR
Drift +50
ppm/ °C
Input impedance 1 MΩ
Signal-to-noise ratio +90 dB
Crosstalk <1 LSB
Programmable Gain:
Gain software
selectable,
1, 2, 5,or 10V/V
Settling time 3.5 µs to 0.01% all gains
Nonlinearity +0.0003% of FSR
Max. input voltage +40 Volts
Input CMRR 100 dB
Digital Inputs:
Digital inputs 16,
logic level, optically isolated
Input type CMOS logic compatible
Operational mode software selectable,
level sense / latching active high or low
Minimum pulse width 150 ns
Input connectors bits (0 to3) on front panel BNC
16 bits
on rear panel connector
Max. input voltage +40 Volts
Trigger Input:
Number 1
hardware selectable
isolated /
non-isolated
Input type CMOS logic compatible
Operational mode software selectable,
edge mode and invert sense
Minimum pulse width 150 ns
Input connector BNC on front panel
Max. input voltage +40 Volts
Analog Output:
Number of channels 4
pseudo-differential,
optically isolated
Type of DAC double buffered,
multiplying
Output connector BNC
Resolution 18-bit
converter,
16-bit data
(1 in 65536)
Output Range -10.24 to +10.239 Volts
Conversion speed software selectable,
5 µs min
Gain error 0.2% of FSR
Gain linearity <2 dB
Gain drift +25 ppm of
FSR/ °C
Signal-to-noise ratio 116 dB
Output impedance 200 Ω
(for output overload protection)
Short circuit to ground indefinite
Output load current +8 mA typical
Digital Outputs:
Standard
Number 32, optically isolated
Output driver AC, HCT, ACT, HCT, VCT, or 8
TTL loads
Output connectors bits (0 to 3) on front panel BNC
32 bits on dual 50 pin connector
High current drive
Number 14, optically isolated
Output driver AC, HCT, ACT, HCT, VCT, or 8
TTL loads
Output connector 14 bits on DB-25 pin connector
Output sink current 350 mA maximum
Asynchronous outputs
Number 16, non-isolated
Output driver HC logic compatible
Output connector 34 pin connector
Sequencer outputs
Number 7, optically isolated
Output driver AC, HCT, ACT, HCT, VCT, or 8
TTL loads
Output connector 7 bits on dual 50 pin connector
Trigger Output:
Number 1, selectable
isolated /
non-isolated
Output driver AC, HCT, ACT, HCT, VCT, or
8 TTL loads
Output connector BNC on front panel
Max. output current 6 mA
Software and Drivers:
* MacOS classic C/C++ Metrowerks libraries
Carbon
Driver and Framework library
Wavemetrics
IGOR Pro XOP’s
Heka
PatchMaster, Pulse, X-Chart
AxoGraph
InstruTECH
AcquireT
PulseControl
XOP’s
MacOS X (PPC) Driver and Framework
library
Wavemetrics
IGOR Pro XOP’s
Heka
PatchMaster
Heka ChartMaster
Heka PotMaster
AxoGraphX
InstruTECH AcquireT
MacOS X (Intel) Framework library
Wavemetrics
IGOR Pro Carbon XOP’s
Heka
PatchMaster
Heka ChartMaster
Heka PotMaster
AxoGraphX
InstruTECH AcquireT
* Windows 9x, ME, NT, 32 bit C/C++ library, DLL and driver
2000, XP, Vista Wavemetrics IGOR Pro XOP’s
National Instruments LabView
Heka PatchMaster, Pulse, X-Chart, and TIDA
InstruTECH AcquireT and ECELL
Strathclyde WinWCP
AxoGraphX
Linux Driver and
C/C++ library
* No longer supported but still available upon request.
All drivers are available
for download.
A note about Macintosh G5
computers
Apple has once again changed the PCI bus on their Power Mac G5
desktop computers. The latest release, as of November 2005, use’s a PCI
Express bus architecture, this is also true for the Intel based Mac
computers. The PCIexpress bus IS NOT compatible with either the
PCI-18 or PCI-18V3. For these new systems the USB-18 host interface
is available.
Power Mac G5 computers before November 2005, used a 3.3 Volt
PCI /PCI-X bus architecture. These systems are compatible with the
PCI-18V3 host interface.
FIFO Memory:
Standard: 1024 kilosample FIFO
Model Numbers:
ITC-18/PCI: ITC-18
with 5 Volt PCI bus host interface
ITC-18/PCIV3: ITC-18 with 3.3 Volt PCI bus
host interface
ITC-18/USB: ITC-18
with USB 2.0 host interface
OEM versions also available. Please
contact us with your requirements
Power Requirements:
85-264 VAC, 47-440 Hz, 15 Watts
Dimensions:
Width: 19"
Height: 1.75"
Depth: 10.5"
Weight: 8 pounds
Warranty:
One year parts and labor
Specifications are typical at 25oC unless otherwise
noted.
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